An art of inferring an emotion of a person from a voice uttered by the person, or more specifically from a volume of the voice, a waveform of the voice, a pitch of the voice, phoneme, etc., has been disclosed (Patent Document 1). As principal factors of emotion inferred from a certain voice, the six factors of joy, sadness, surprise, disgust, anger, and fear are used in many cases.
Further, Patent Document 2 discloses an information processing terminal making use of the above art of inferring a person's emotions to specify an emotion from a voice during voice call and reproducing, on a display, a still image or moving image that can be associated in one glance with the specified emotion.
Patent Document 1: International Patent Publication No. WO 00/62279
Patent Document 2: Japanese Published Unexamined Patent Application No. 2006-106711